1. The inner wall of the pipe is combined with the outer wall. The outer wall has an axial adjacent gap, extending outward from the outer wall. There is an outer wall inside the pipe. The outer wall is combined with the outer wall, and the outer wall has an adjacent shell part;

摘要

With a Drill Pipe that extends axially defined by a Smooth Inner wall is FUSED to a corrugated outer wall is axially adjacent edges, annular,That extend outward and separated by gaps. Includes method.